Heater Core - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blunova · 07-03-2002, 09:44 AM

This morning on the way to work I had a cloud of steam come through the vents and a strong antifreeze smell. I'm thinking its the heater core. What is involved with changing it out? Now I have a reason to work on my truck this 4th of July weekend!!!
Thx

Low69CST · 07-03-2002, 09:49 AM

Is your truck A/C? If it is, your in for a hell of a job.

Blunova · 07-03-2002, 10:00 AM

No its non a/c

Southpa · 07-03-2002, 10:01 AM

Before you go buying parts have a look at it first, could have just been a hose coming loose or rupturing. Never been inside that area of my truck. However, I had it happen to me in a previous vehicle on the hwy. Lucky I had a friend with a squeegy in the passenger seat to periodically clean the windows off so I could see! In my case (78 Monte) is was just a hose coming loose. I think I got at it from under the dash, can't really remember...

jmj4 · 07-03-2002, 11:42 AM

taking the fiberglass heater core cover off will make you curse the designers of these trucks. basically to get to all the bolts that hold it to the firewall you have to drop the inner fenderwell, at least this is what i decided after several attempts and riding around with no heat for a year. then once you get it off, you'll have to unbolt it from the cover. but to even access the hose connections you have to remove the cover.

Low69CST · 07-03-2002, 11:44 AM

GM heating and A/C designs suck.

jbynum · 07-03-2002, 01:44 PM

I just this weekend replaced the heater core in my (newly acquired) CST10 w/402 big block & A/C.

It took me about 2 hours. I removed the glove box, & the air box (the one that has all of the hoses attached). I removed the 4 nuts from the OUTSIDE of the fiberglass box. I DID NOT drop the fenderwell. Instead I used a universal on a 3/8" LONG extension. Piece of cake. I removed the 4 inside bolts, & the heater hoses. I pulled it out, & simply replaced in reverse order.

I have installed heater cores in my 85 Chevy C20, a 76 Olds Delta, & an 83 Olds Delta. The install on this 70 Chevy CST10 was BY FAR the easiest I have ever encountered!

TonyM · 07-03-2002, 03:23 PM

This has happened to me a couple of times...That heater core box has some bolts that are a *$&*#^ to get off because they are in an impossible place to get at.. between the inner fender and the cab. Easy way... don't recomment, but works. Remove a few of the upper bolts, then using a little saw, make a cut from the top hole for the heater core, to the top of the box, then one down to the bottom hole. pry apart and remove, replace with a new one, bolt the box back to the cab, then fiberglass. This works, but isn't particularly pretty.

The second way that I know of, unless you can get at those nastly little bolts, is to remove the inner and outer fenders. GOOD LUCK!
TOny

Longhorn Man · 07-03-2002, 05:34 PM

You guys are complaining about dropping a fenderwell to do a heater core??!!!! Try pulling the dash in a van, or in an escort, or 75% of the vehicles made in the last 25 years.
These trucks are easy.
Drop the fender well.
Remove bolts holding on cover.
Check for goop or sillicon holding heater box on. If there is some, use a putty knife to cut it, if you just yank on it, you could break it...it is 30+ years old.
Swap out old for new. Available in any parts store.
put it all back together.
I normally leave the lower hardware off from the box, then next time you do it, you won't have to pull the fenderwell. HOWEVER, you will get exhaust fumes from time to time, and a less efficient heater.

07-03-2002, 09:44 AM	#1
Blunova Registered User Join Date: Dec 2000 Location: Noble, OK USA Posts: 125	Heater Core This morning on the way to work I had a cloud of steam come through the vents and a strong antifreeze smell. I'm thinking its the heater core. What is involved with changing it out? Now I have a reason to work on my truck this 4th of July weekend!!! Thx __________________ 69 C10 65 Chevy II

07-03-2002, 09:49 AM	#2
Low69CST Registered User Join Date: May 2000 Location: Frankfort, Kentucky, USA Posts: 2,163	Is your truck A/C? If it is, your in for a hell of a job. __________________ '69 CST Short fleetside Lowered, 400 small block, 700R4, 4 wheel disc brakes, front sway bar & rear camaro sway bar (in progress) '87 V10 4x4 Short Fleetside Quad Suspension and Dual Tanks

07-03-2002, 10:00 AM	#3
Blunova Registered User Join Date: Dec 2000 Location: Noble, OK USA Posts: 125	No its non a/c __________________ 69 C10 65 Chevy II

07-03-2002, 10:01 AM	#4
Southpa Registered User Join Date: May 2000 Location: Victoria, BC, Canada Posts: 2,409	Before you go buying parts have a look at it first, could have just been a hose coming loose or rupturing. Never been inside that area of my truck. However, I had it happen to me in a previous vehicle on the hwy. Lucky I had a friend with a squeegy in the passenger seat to periodically clean the windows off so I could see! In my case (78 Monte) is was just a hose coming loose. I think I got at it from under the dash, can't really remember... __________________ 1970 GMC 1500 Custom Original 350/TH350 Victoria, BC, Canada You can wish in one hand and crap in the other. See which one gets filled first.

07-03-2002, 11:42 AM	#5
jmj4 Registered User Join Date: Dec 1999 Location: Mississippi Posts: 119	heater core cover taking the fiberglass heater core cover off will make you curse the designers of these trucks. basically to get to all the bolts that hold it to the firewall you have to drop the inner fenderwell, at least this is what i decided after several attempts and riding around with no heat for a year. then once you get it off, you'll have to unbolt it from the cover. but to even access the hose connections you have to remove the cover. __________________ 1970 GMC Custom 1500 SWB 307/TH350 3.73 Positrac

07-03-2002, 11:44 AM	#6
Low69CST Registered User Join Date: May 2000 Location: Frankfort, Kentucky, USA Posts: 2,163	GM heating and A/C designs suck. __________________ '69 CST Short fleetside Lowered, 400 small block, 700R4, 4 wheel disc brakes, front sway bar & rear camaro sway bar (in progress) '87 V10 4x4 Short Fleetside Quad Suspension and Dual Tanks

07-03-2002, 01:44 PM	#7
jbynum Registered User Join Date: Jun 2002 Location: Brandon, Mississippi Posts: 13	I just this weekend replaced the heater core in my (newly acquired) CST10 w/402 big block & A/C. It took me about 2 hours. I removed the glove box, & the air box (the one that has all of the hoses attached). I removed the 4 nuts from the OUTSIDE of the fiberglass box. I DID NOT drop the fenderwell. Instead I used a universal on a 3/8" LONG extension. Piece of cake. I removed the 4 inside bolts, & the heater hoses. I pulled it out, & simply replaced in reverse order. I have installed heater cores in my 85 Chevy C20, a 76 Olds Delta, & an 83 Olds Delta. The install on this 70 Chevy CST10 was BY FAR the easiest I have ever encountered! __________________ 1970 CST10 402 Big Block Black/Gold Brandon, MS

07-03-2002, 03:23 PM	#8
TonyM Registered User Join Date: Jan 2000 Location: British Columbia, Canada Posts: 208	This has happened to me a couple of times...That heater core box has some bolts that are a $&#^ to get off because they are in an impossible place to get at.. between the inner fender and the cab. Easy way... don't recomment, but works. Remove a few of the upper bolts, then using a little saw, make a cut from the top hole for the heater core, to the top of the box, then one down to the bottom hole. pry apart and remove, replace with a new one, bolt the box back to the cab, then fiberglass. This works, but isn't particularly pretty. The second way that I know of, unless you can get at those nastly little bolts, is to remove the inner and outer fenders. GOOD LUCK! TOny __________________ 68GMC in family since new Victoria, B.C. Canada

07-03-2002, 05:34 PM	#9
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	You guys are complaining about dropping a fenderwell to do a heater core??!!!! Try pulling the dash in a van, or in an escort, or 75% of the vehicles made in the last 25 years. These trucks are easy. Drop the fender well. Remove bolts holding on cover. Check for goop or sillicon holding heater box on. If there is some, use a putty knife to cut it, if you just yank on it, you could break it...it is 30+ years old. Swap out old for new. Available in any parts store. put it all back together. I normally leave the lower hardware off from the box, then next time you do it, you won't have to pull the fenderwell. HOWEVER, you will get exhaust fumes from time to time, and a less efficient heater.

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